Mapping and navigation systems typically determine the relative position of a user based upon positioning signals received from one or more land-based beacons, one or more orbiting satellites comprising the Global Positioning System (“GPS”), or other sources. Based upon these positioning signals, the mapping and navigation system can determine other navigational data, such as the present latitude and longitude position and the present compass heading, course over ground, bearing and speed over ground. In addition, mapping and navigation systems allow the operator to enter several event markers to identify specific positions and several waypoints to mark a course which the operator desires to follow. Accordingly, the mapping and navigation system can also determine the distance and bearing to the nearest event marker or to the nearest waypoint based upon the positioning signals.
In order to record historical positioning data, many GPS systems have recording and storage elements to allow waypoints and event markers to be stored for later use. For example, it is often desirable to mark a location with otherwise undefined map features for later return. Maps often include only the most relevant highways markers, elevation contours, and notable landmarks. When none of these distinguishing features are present, then marking a position may be helpful for future purposes, such as return or event marking. In navigation systems that do include event and waypoint markers, the event markers are limited to position and perhaps a brief identifier. If additional data is necessary, it might be manually written in an accompanying log or the like. Accompanying logs, however, require carrying additional materials, which may not always be desirable when using these systems.
In addition to referring to maps, such as paper maps or graphically displayed maps, in order to determine navigational information, boaters and sport fishermen commonly employ sonar systems, such as sonar depth finders and sonar fish finders, to provide detailed information regarding the contour of bottom surface of the body of water and objects submerged therein. A number of sonar systems have been developed which display the reflected sonar signals in a variety of manners. For example, some sonar systems include rotating disk lamps or “flashers” which produce a pulse of light upon the reception of a reflected sonar signal.
Other sonar systems were developed that included a chart recorder in order to provide historical mapping data indicative of the contour of the bottom surface of the body of water as well as the relative location of submerged objects, such as fish. These sonar mapping systems generate a strip chart on which markings indicate the contour of the bottom surface of the body of water as determined from the reflected sonar signals. Still, other sonar mapping systems having display devices have been developed to provide a historical graphical display of the bottom surface of the body of water over which the boat is passing as well as to identify submerged objects from which the sonar signals reflect. The associated display devices typically include cathode ray tubes, electroluminescent panels, liquid crystal displays and LED displays. These sonar systems also generally include advanced electrical circuitry, including one or more microprocessors or microcontrollers.
Microprocessors and microcontrollers not only provide a number of features that allow the operator to customize the resulting display, but are also easily adapted to permitting historical mapping of sonar data to be stored in memory. In particular, external memory systems allow storage and subsequent transfer to other compatible systems. One example of external storage in use today includes MMC cards, which is a flash memory storage and typically compatible numerous electronic systems including most home computers. External storage, therefore, permits a user to maintain historical data in other areas besides the sonar and navigation mapping systems themselves.
The above described sonar mapping systems and position mapping systems have, on occasion, been integrated into single systems relevant for marine fishing and navigation purposes. The features described above, when integrated into a single system, permit historical sonar and position data to be stored for future reference. As described above, however, these systems are limited in the amount of data that can be provided. In particular, subjective data regarding a location or sonar conditions at a location are not recorded by these systems. For example, it may be advantageous to identify a location by the events that happen, like the observation of fish concentration, or the objects that you see, such as the hull of a shipwreck sticking out of the water. While event logs may permit maintaining such data, they still require additional supplies, and it is often cumbersome or inconvenient to take the time to prepare journal entries to maintain such data. Therefore, it would be advantageous to provide an alternative method or apparatus to record such data.